what you say is true, thrax...
but here's a fan's perspective. up until recently, i considered starsiege to be part of the Tribes universe.
that was until i read the backstory and materials regarding starsiege from the SS:2845 site, and realized that the Starsiege universe, which had its conceptual roots waaaaay the hell back, was all one and the same all the way through tribes 2. the decision to distance tribes from starsiege wasn't made until after t2 was already in developement, as i recall.
but a great effort was made to make sure that the universes still had consistent backstory - the rise of the Bioderms, who were originally mentioned back in the SS franchise as a sidepoint that was pretty minor.
We're in a heady game of semantics, here, one which no one's gonna win. Saying "it's this name because it's MY franchise" is really insulting to those of us who have enjoyed the SS universe as a whole, instead of the tiny little backstory behind tribes alone.